This invention relates to a mechanical release arrangement for a fluid-pressure-operated braking cylinder having an emergency brake/parking brake feature, such a brake cylinder as can be used in motor vehicle brake systems. A number of known mechanical brake release arrangements typically have required a large number of components, the majority of which had to be manufactured to precise tolerances. Additionally, such arrangements were designed such that the release portion components, which bridged the emergency portion and the brake actuating portion of the system, were subjected to excessive shear forces which, as a consequence, forced maintenance and repair expenditures higher.
An example of such a release arrangement can be found in German Pat. DE No. 22 09 570. In this arrangement, a sleeve connected to a piston has a longitudinal slit running the approximate length thereof, and further, has a transverse slit intersecting the longitudinal slit at a point along the circumference of the sleeve. A cam is secured to a piston rod such that, the cam is movable in the manner of a bayonet closing within the longitudinal slit of the sleeve during release conditions. The piston rod, cam arrangement is prevented from axial movement relative to the sleeve and piston during normal brake operating conditions due to the engagement of the cam within the transverse slit at this time; such engagement allowing coincident movement of the piston rod with the piston and sleeve configuration. This engagement between the cam and the transverse slit on the sleeve, however, has resulted in the disadvantage of a significant shear force exhibited on the respective components at what is a relatively small contact surface area. This disadvantage has proven costly in terms of component wear, maintenance, and repair.